dragon's head vs Dracocephalum parviflorum

dragon's head and Dracocephalum parviflorum both are nouns.

Word	Noun	Adjective	Verb	Adverb
dragon's head	Yes	No	No	No
Dracocephalum parviflorum	Yes	No	No	No

As nouns, dragon's head and Dracocephalum parviflorum are synonyms defined as:

dragon's head and Dracocephalum parviflorum: American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers

Other synonyms of dragon's head include dragonhead.

dragon's head (noun)	Dracocephalum parviflorum (noun)
American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers	American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers